1. The Field of the Invention
The present invention relates generally to valve assemblies for use in managing flow through fluid conduits. More particularly, the present invention relates to a dry break valve assembly that releasably joins two fluid conduits in such a way that separation of constituent portions of the dry break valve assembly automatically terminates fluid flow from each of the respective conduits, and thereby substantially prevents material leakage of the fluid.
2. The Prior State of the Art
In recent years, environmental concerns have been receiving significantly more attention, and various governmental agencies have responded by implementing stringent regulations to reduce or prevent pollution. Many of these regulations and concerns are directed towards those industries that transport fluids. For example, it is very difficult to transport a fluid without spilling or leaking some of the fluid into the environment. Thus, some environmental regulations require that minimal leaking occur during handling, processing, or transportation of the fluid.
These environmental concerns become especially clear when considering the magnitude of the industries that handle fluids that can cause significant damage in small quantities. There is a concern, therefore, to protect both the public and the environment from these types of fluids. While some fluids that are transported, such as water and milk, may not pollute the environment when they are leaked or spilled, the loss of fluid into the environment is nevertheless viewed as a general waste of resources. More generally, the loss of fluid into the environment is not desirable even if the fluid does not contribute to pollution.
Within the transportation industry, a variety of different devices are used to transport a fluid from a source to a destination. These devices often use valve assemblies and conduits of various types to both connect the source to the destination as well as to manage fluid flow through the conduit. Usually, the conduit is pressurized to direct fluid toward the desired destination. With each transfer of fluid, there is a risk that leakage will occur due to human error, equipment malfunctions, or the like. As previously stated, it is desirous and often critical to ensure that the spills or leaks are substantially minimized.
A common source of fluid leaks and fluid spills are the valves that are used to connect a fluid source to a fluid destination. Various types of valves have been designed to stop (i.e., check) the fluid flow when the valve is manually disassembled. One known device for checking fluid flow is a ball check valve. A ball check valve is essentially a ball (i.e., a check ball) which rests against a ball seat to form a valve. An operator may use the ball check valve to initiate or terminate the fluid flow. Despite the checking feature of the ball check valve, a problem exists in the integrity of the fluid transfer system when the valve or conduit undergoes stress.
When the conduit and the valve are subjected to forces such as stretching, pulling, twisting, and the like, the fluid being transferred through the conduit and the valve may leak or spill into the environment. More particularly, the conduit, rather than the ball check valve, is likely to rupture or otherwise malfunction in the presence of these forces. Thus, while the ball check valve is appropriate for checking fluid flow, it does not prevent spillage or leakage when subjected to external stress. Because the conduit is likely to rupture or otherwise malfunction in these types of situations, the spillage or leakage of fluid into the environment can be significant because the fluid flow can no longer be checked.
For example, when a fuel transport vehicle is delivering liquid through a conduit such as a hose into a fuel tank, the hose is attached to the vehicle at one end and to a fuel tank at the other end. A valve such as a ball check valve may be disposed at the vehicle end of the hose such that fluid communication through the hose may be established or checked. If the vehicle drives away with the hose connection still intact, the connection will break or rupture. Because the hose is the weakest part of the connection, the break usually occurs somewhere in the hose and fluid escapes out into the environment. In this example, the ball check valve typically does not disassemble because it is much stronger than the hose. Even if the ball check valve were to break instead of the hose, fluid would still leak from either the source of the destination of the fluid.
The previous example illustrates the need, especially with highly toxic chemicals or hazardous wastes, for a valve assembly that is designed to automatically disassemble when there is excessive force in the fluid transport system that threatens to break the conduit. In addition, the checking feature of the valve assembly should operate automatically and at substantially the same time as the automatic disassembly of the valve.
Further, with the trend toward automating fluid transfer processes, there is a need for safety mechanisms that are automated. For example, fuel transfer systems are under development wherein tankers drive into a delivery unit, automatically hook up the fuel delivery system, transfer the fuel, and exit the delivery unit with minimum human intervention. In this situation, it is critical that safety mechanisms are provided because of the lack of error detection by humans.
In view of the foregoing problems, it would be an advancement in the art to provide for a device that resolves at least the aforementioned problems. In particular, the device should automatically disassemble upon application of a predetermined force and should automatically check fluid flow of the conduit such that leakage is substantially prevented from both the source and the destination of the fluid.
The present invention has been developed in response to the current state of the art, and in particular, in response to these and other problems and needs that have not been fully or adequately solved by currently available fluid system components. Thus, it is an overall feature of embodiments of the present invention to provide a dry break valve assembly that resolves at least the aforementioned problems. It is a further feature of the present invention to provide a dry break valve assembly that will automatically terminate or check flow from two conduits joined by the dry break valve assembly, upon separation of constituent parts of the dry break valve assembly. It is yet another feature of the present invention to facilitate the flow of fluid through a valve assembly.
In one embodiment, the dry break valve assembly provides two essential safety features to prevent substantial leakage during transfer of fluids. An automatic separation feature is provided which automatically disassembles the valve assembly upon application of a predetermined force. For example, such a force may occur when a truck drives away from a tank before uncoupling the dry break valve which facilitated the transfer of fluid from the truck to the tank. The separation or disassembly feature causes the valve to disassemble while minimizing spillage or leakage of the fluid. The spillage or leakage is minimized by an automatic checking feature that stops fluid flow when the valve assembly is disassembled in this manner. The checking feature may also be used when the dry break valve is used in normal operations.
The valve assembly includes a cam mechanism which keeps the valve gates within the valve open, establishing fluid communication. Essentially, when the valve assembly is fully opened, the cam mechanism automatically locks into place as a result of the equilibrium of torque forces and spring forces. The lock is released when the valve assembly is disassembled and the valve gates close automatically, thus providing an automatic check valve feature.
The valve can be disassembled manually or automatically. The valve assembly has a first housing and a second housing which are maintained in sealing engagement by a sleeve. The sleeve can be further divided into two portions, which are kept in sealing engagement with a collar and a breakable link assembly. The automatic separation or disassembly feature is permitted in one embodiment by the collar and breakable link assembly. The breakable link assembly is configured to support a predetermined amount of stress. When the valve assembly is subjected to forces beyond that predetermined stress point, the shear pin fails, releasing the collar from engagement with the sleeve. The separation of the collar releases the valve assembly from sealing engagement and initiates the automatic check valve feature.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.